minor #10986 format option deprecation for HTML 5 widgets (xabbuh)

This PR was merged into the master branch.

Discussion
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format option deprecation for HTML 5 widgets

document the deprecations that will be introduced with symfony/symfony#28723

Commits
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f4597bf format option deprecation for HTML 5 widgets

Author: javiereguiluz

reference/forms/types/date.rst

@@ -170,6 +170,11 @@ values for the year, month and day fields::
 
 .. include:: /reference/forms/types/options/date_format.rst.inc
 
+.. versionadded:: 4.3
+
+    Using the ``format`` option when the ``html5`` option is enabled is deprecated
+    since Symfony 4.3.
+
 .. include:: /reference/forms/types/options/html5.rst.inc
 
 .. _form-reference-date-input:

reference/forms/types/datetime.rst

@@ -138,6 +138,11 @@ used by the HTML5 ``datetime-local`` field. Keeping the default value will
 cause the field to be rendered as an ``input`` field with ``type="datetime-local"``.
 For more information on valid formats, see `Date/Time Format Syntax`_.
 
+.. versionadded:: 4.3
+
+    Using the ``format`` option when the ``html5`` option is enabled is deprecated
+    since Symfony 4.3.
+
 .. include:: /reference/forms/types/options/hours.rst.inc
 
 .. include:: /reference/forms/types/options/html5.rst.inc